By carefully reading the problems, you will notice that you need the formula for the area of a triangle to answer Exercise 41. If necessary, review the list on page 28.

Also notice that while both exercises involve using formulas, different skills are involved:

In Exercise 41, you will need to solve a formula for one variable in terms of the other. You may find it helpful to review Example 5 on page 28.

In Exercise 42, the relationship between two variables is described in words, rather than in an explicit formula. Use the information to write a verbal model, then assign labels and write an algebraic formula.